Chemical process and product



Patented Dec. 24, 1946 2,418,256 CHEMICAL PROCESS AND PRODUCT Frank J.Soday, Swarthmore, Pa., assignor to The United Gas Improvement Company,a corporation of Pennsylvania No Drawing. Application September 9, 1942,

Serial No. 457.743

This invention i concerned with the refining of unsaturatedhydrocarbons.

More particularly, this invention is concerned with the removalofimpurities from unsaturated hydrocarbons and unsaturated hydrocarbonfractions by the application of metals in group Ia and group IIa of theperiodic table and certain active alloys or derivatives thereof in thepresence of a polymerization inhibitor.

It is an object of the present invention to continuously purifyunsaturated hydrocarbon fractions, and particularly diolefine fractionsby treatment with one or more alkali or alkaline earth metals, or activealloys or derivatives thereof, in the presence of one or morepolymerization inhibitors under carefully controlled conditions.

6 Claims. (Cl. 260-6815) ably in a continuous manner, by the applicationAnother object ofthe invention is. the provision of certain methodswhereby unsaturated hydrocarbon fractions and particularly diolefinefractions, may be purified in a continuous manner by the application ofalkali or alkaline earth metals in the presence of one or morepolymerization inhibitors without undue loss of unsaturatedhydrocarbons, in the form of soluble or insoluble polymers. Otherobjects and advantages of the invention will be apparent to thoseskilled in the art upon an inspection of the following description andclaims.

Unsaturated hydrocarbons and unsaturated hydrocarbon fractions,particularly the latter, frequently contain substantial quantities ofimpurities, such as acetylenic compounds; oxygenated compounds such asaldehydes and peroxides; and the like; which interfere material in mostif not all, cations.

Thus, diolefines and diolefine fractions, parindustrialapplifinely'divided form of at least one metal of group Ia and groupIIaof the periodic table, as well as certain active alloys or derivativesthereof, in the presence of one or more polymerization inhibitors.Particularly desirable results are obtained by the use of finely dividedalkali and alkaline earth metals in the presence of polymerizationinhibitors.

. Examples of refining metals which may be used for such purpose arelithium, sodium, potassium, rubidium, caesium, barium, strontium andcalcium. Due to the availability and low cost of sodium and potassium,however, these metals are preferred for the use set forth herein.

with the use of such ticularly the latter, frequently containsubstantial quantities of acetylenes, such as monovinyl or otheracetylene, oxygenated compounds such as aldehydes and peroxides, as wellas certain other impurities.

As an example, a 41% light oil butadiene frac- .tion obtained by thepyrolysis of petroleum in the gas phase at temperatures substantiallyabove 1300 F., followed by condensation and fractionation, was found tocontain 0.9% mainlymonovinylacetylene, and 0.045% aldehydes, as well ascertain other impurities, including some C3 and C5 impurities. Thisbutadiene fraction, as well as the more highly concentrated butadieneobtained therefrom by the use of suitable concentratlng methodasuch as98% butadiene concentrate, is unsuited for the production of syntheticrubber of good quality due to the inhibiting of acetylenes,

finely divided metals in v hibitors for refining diolefines anddiolefine Alloys of these metals, such as NaPbm, NaHg4, Nacas, NaZmz,KNa, and the like, also may be employed for the removal of undesiredimpurities from unsaturated hydrocarbons and unsaturated hydrocarbonfractions in the presence of one or more polymerization inhibitors. Ingeneral, the alloys of the respective metals react with the impuritiespresent in such hydrocarbons and hydrocarbon fractions at a, slower ratethan the corresponding metals.

- Compounds of these metals which may be employed in the refiningprocess described herein include hydrides, such as LiH, NaH, KH, RbH,and CaH; amides such'as sodamide and potassium amide; and otherreactivecompounds, such as sodium methylate and sodium ethylate.

In general, therefore, it may be said that very group Ia and H11 of theperiodic system, their reactive alloys, and reactive derivatives, may beused to refine unsaturated hydrocarbons and unsaturated hydrocarbonfractions with very satisfactory results in the presence of one or morepolymerization inhibitors. I find that these material are particularlydesirable for use in finely divided form in the presence of infractions.

Inhibitors which are particularly effective agents for retarding therate of polymerization of unsaturated hydrocarbons, and particularlydiolefines and diolefine fractions, when refined with very finelydivided metals inv groups'lq and 11a of'the periodic system, theirreactive alloys,

and reactive derivatives, may be classified in the following groups.

1. Amines and nitrogen-containing inhibitors, particularly aryl amines,such as Alpha-naphthylamine, Thiodiaryl amine,

p-Phenylene diamine, o-Phenylene diamine, 2,4-diamino diphenylamine,Phenyl hydrazine,

Benzamide,

Cyclohexyl naphthyl amine, and Polybutyl amines.

Particularly desirable results have been ob- 5 tained by the use ofsecondary aryi amines having the following general formula I i m-N-m-N-aand H i R1I I R11 R|-N-R in which R and R1 have the same meaning asbefore.

Secondary amines containing'one or more aryl or substituted aryl groupsare preferred, such as a 40 Diphenyl-p-phenylene diamine,Phenyl-beta-naphthylamine, Isopropoxydiphenyl amine,

(and polymers Aldol-alpha-naphthyl amine thereof), Symmetrical (11 beta,naphthyl-p-phenylenediamine,

Trimethyl dihydroquinoline (and polymers there- Ditolylamines, andmixtures thereof 2. Phenolic compounds, such as 3. Compound inhibitors,such as Acyl-substituted amino phenols 4-cyclohexyl amino phenol p-Aminophenol o-Amino phenol 5-amino-2-hydroxytoluene 4 4. Miscellaneousinhibitors, such as Hydroquinone Quinol Nitroso naphthols QuinhydroneReaction product of an aldehyde and an amine p-Amino acetophenoneDihydroxy anthraquinone Reaction product of a ketone with an amine.

Excellent results have been btained when one or more inhibitors selectedfrom a list comprising (1) secondary aryl amines such as phcnylbetanaphthylamine, diphenyl-p-phenylene diamine, isopropoxydiphenylamine, aldol-alpha-naphthylamine (and polymers thereof), symm.iii-betanaphthyl-p-phenylene diamine, trimethyl dihydroquinoline (andpolymers thereof), and the ditolylamines; (2) phenolic compounds, suchas ptertiary butyl cateohol and alkylated polyhydroxy phenols; and (3)reaction products of a ketone, such as acetone, and/or an aldehyde, suchas formaldehyde and acetaldehyde, with an amine, such as aniline.

In general, I' prefer to employ less than 10%, by weight, ofpolymerization inhibitor, based on the unsaturated hydrocarbon orunsaturated hydrocarbon fraction in batch treating processes, and themaximum total volume of suspending liquid in the treating system at anyone time in the case of continuous treating processes. Good results alsohave been obtained by the use of less than 5% inhibitor and even 2%inhibitor in certain cases, particularly when oneor more of theinhibitors listed in the preceding paragraph are employed.

The diolefines and diolefine fraction employed in my process, such asbutadiene, may be obtained 'from any desired source such assynthetically, for

example by the removal of the elements of chicrine or hydrogen chloridefrom polychlorinated C4 compounds, by the partial hydrogenation ofmonovinylacetylene, by the dehydrogenation of butanes and/or butylenes,and by the dehydration of C4 alcohols and glycols; by the pyrolysis ofpetroleum and petroleum hydrocarbons, such as by the pyrolysis ofpetroleum in the gaseous phase at temperatures above 1000 F., and moreparticularly above 1300 F., followed by condensation and fractionation;and by the pyrolysis of other materials, such as by the pyrolysis ofcyclohexane or by the pyrolysis of alcohols, such as the pyrolysis ofethyl alcohol. In the latter case, the process may include a combinationof dehydrating and/or pyrolytic reactions. Thus, it may be carried outby passing the alcohol at suitable temperatures over suitable catalyticagents, such as for example alumina and the like, followed by secondarypyrolysis, or recombination steps, if desired. Other procedures also maybe employed for the production of butadiene or butadiene fractions whichmay be refined by the methods to be more particularly described herein.

The diolefine or diolefine fractions also may be initially concentratedto any desired extent prior to refining, and such concentration may becarried out by any desired method. This may include concentration byfractionation, azeotropic distillation, solvent extraction, acombination of solvent extraction and fractionation methods, and theformation of complexes between the diolefine and some active compound,such as cuprous chloride, followed by the removal of the non-diolefineportion of the fraction and the decomposition of the complex. Otherconcentrating methods also may be employed if desired.

In addition, other refining methods also may be applied to diolefinesand diolefine fractions to more particularly described herein. Thus,such fractions may be contacted with acids or acidic I solutions ormaterials to remove a portion of certain impurities or undesirablematerials present. Thus, light oil butadiene fractions may be contactedwith sulfuric acid to remove at least a portion of the isobutylenepresent.

Such concentrating and/or partial refining operations also may beapplied to the diolefine or diolefine fractions subsequent to therefining operations to be more particularly described herein.

I find that a solution of sodium, or a suspension or emulsion of veryfinely divided sodium, or a solution, suspension, or emulsion of one ormore sodium alloys or active compounds, is a particularly desirableagent for the continuous removal of certain undesirable impurities fromunsaturated hydrocarbons and unsaturated hydrocarbon fractions, andparticularly from diolefines and diolefine fractions, when carried outin the presence of at least one polymerization inhibitor. Excellentresults are obtained by the use of a suspension of very finely dividedsodium containing an inhibitor.

The refining method disclosed herein difiers fundamentally from allmethods described heretofore for the refining of unsaturatedhydrocarbons or unsaturated hydrocarbon fractions in that the materialin question is treated with. a-

metal of group Ia or group IIa, or an active alloy or compound of suchmetals, in finely divided or solution form in the presence of atleastone polymerization inhibitor. By the use of a polymerization inhibitor,the loss of valuable hydrocarbons due to polymerization is very markedlyreduced, or almost completely eliminated.

This is of particular importance in the case of diolefines, such asbutadiene, which are quite susceptible to polymerization when placed incontact with certain active metals, as well as active alloys andderivatives thereof. Thus, sodium isa very active catalyst for thepolymerization of butadiene and is employed for this purpose in severalindustrial processes, notably in Russia. The use of this material invery finely divided form for the refining of butadiene, therefore,

must be carried out within well defined limits in order to prevent undueloss of butadiene due to polymerization. The success of the refiningmethod employing finely divided sodium, or other active metals, alloys,or compounds, depends to a very considerable extent upon the presencetherein of a. polymerization inhibitor. understood, of. course, that aninhibitor must be very specific and powerful in action in order to re-'tard the rate of polymerization of unsaturated hydrocarbons, such asbutadiene, in the presence of a very active catalyst, such as finelydivided 7 sodium.

The refiningoperationsmay be carried out in any desired manner such asbatch, multiple batch, batch countercurrent, continuous, and

continuous countercurrent operations. Although- It will be tion,

I prefer to conduct it in a vertical vessel or tower in which a certainheight of a liquid suspension or solution of the active refining agentcontaining an inhibitor is maintained. This mixture of active refiningagent and inhibitor will'be referred to herein as the refining reagent.The material to be refined is passed upward through this column ofreagent at a rate sufficient to insure the removal of the desiredquantity and type of impurities present at the temperature employed.

Reference is made to mycope'nding applica- Serial No. 457,475, filedSeptember 5, 1942, now U. S. Patent 2,398,810. issued April 23, 1946,disclosing and claiming the refining of unsaturated hydrocarbonsandunsaturated hydrocarbon fractions with a finely divided active, metalfrom groups'Ia and Ba ofthe periodic system, or

an active alloy or compound thereof, in a continuous system.

treated and the refining reagent also may be employed if desired. Thus,the unsaturated hydrocarbon may be passed through a horizontal treatingunit, such as a pipe 'or bank of pipes, containing a suspension of thedesired refining reagent, or otherwise.

The suspending liquid employed for the preparation of the refiningreagent may be of any desired type, provided that it does not react withany of the constituents of the refining reagent or the material to betreated to any substantial extent, and provided that it'does notintroduce any additional impurities into the material to be treated. Ifind that hydrocarbons and hydro carbon fractions are particularlydesirable materials for use as suspending mediums-for refining reagentsof the type described herein. Excellent results have been obtained bythe use of aromatic hydrocarbons and aromatic hydrocarbon fractions forthis purpose.

It is to be understood, of course, that the material to beTreateddissolves to some extent in the suspending medium, consequently thesuspending medium actually employed in. theoperation of the processusually comprises a mixture of the material to be treated and thesuspending medium initially introduced into the system. Thus, in thetreatment of a light oil butadiene fraction with a xylene suspension offinely divided sodium containing an inhibitor in a continuous systemoperating at 50 C. and atmospheric pressure, the suspending mediumcontained 11% of the butadiene fraction by weight after equilibriumconditions had been established.

In a similar manner, when refining a light oil butadiene fraction in acontinuous system with a xylene suspension of finely divided sodiumcontaining an inhibitor at 50 C. and a pressure of 50 pounds per squareinch, gauge, the composition of the suspending medium after equilibriumconditions had been established was 76% butadiene fraction and 24%xylene. r

The material being treated also may serve as a suspending medium for therefining reagent without the addition of any other material, if desired.Thus, a light oil butadiene fraction may be introduced into the desiredtower or vessel, together with the finely divided refining agent andinhibitor, after which the butadiene fraction is passed into thesuspension of the refiningagent containing inhibitor in-the butadienefraction at the desired temperature, the charging rate and moreparticularly the operating pressure 7 being adjusted to maintain therefining agent at the desired level in the vessel.

Itis to be understood, of course. that the portion of the material to betreated which has been dissolved in the suspending medium or which hasbeen employed as the suspending medium in the substantial absence ofother liquid materials, does not necessarily remain in the treating zonethroughout the entire treating cycle. Rather, this material is in astate of dynamic equilibrium with the material being treated, a portionof it volatilizing continuously and being removed from the system,thematerial volatilized in this manner being replaced by the solution of acorresponding quantity of freshly added material to be treated. Themajor portion of the material to be treated, of course, bubbles upthrough the suspending medium without dissolving therein.

The thickness of the layer of refining reagent through which thematerial to be treated is pref erably passed depends upon a number offacbe employed, depending upon the type and concentration of thefraction to be refined, the temperature, the depth of reagent employed,and the like, 'I generally prefer to employ a refining reagentcontaining less than 30%, and more particularly less than 20%, by weightof the treating agent. Excellent results are obtained when less than byweight of the treating agent is suspended in the suspending medium.

It is to be understood, of course, that the t rm suspending mediumrefers to the actual suspending agent employed during the treatingoperation, and includes any of material being treated which 1 maydissolve in such agent.

tors, such as the quantity and type of impurities present, the type andquantity of inhibitor employed, the extent to which such impurities areto be removed, the type and degree of dispersion of the treating agentemployed, the reaction temperature, the concentration of the treatingagent in the suspending medium, and the like. In general, however, Iprefer to employ a layer of refining reagent at least one foot thickand, more preferably, at least two feet thick. Excellent results areobtained by the use of a layer of refining reagent at least four feetthick.

It will be recognized that, other things being equal, the depth ofrefining reagent employed in the treating vessel controls the contacttime between the material to be refined and the refining reagent.

The degree of dispersionof the treating agent also has a very profoundeffect upon the degree of refining obtained. In the case of sodium, Iprefer to employ a subdivided mass in which at least the majority of theparticles present have a diameter of not more than 0.05" and, morepreferably, not more than 0.03". Excellent results are obtained when atleast the majority of the particles present have a diameter of not morethan 0.02".

This subdivision maybe carried out in any desired manner. Thus, in thecase of sodium, a solution of this material in liquid ammonia may beintroduced into an inert liquid, such as xylene, at room temperature orat elevated temperatures. The almost instantaneous volatilization of theammonia present results in the dispersion of the sodium present in thexylene inan extremely finely divided state. Another method comprisesspraying molten sodium into an inert liquid such as xylene or solventnaphtha. By suitable variations in. the type and degree of fineness and/or dispersing ability of the spray nozzle employed, sodium of almost anydesired degree of fineness may be obtained at will.

Another satisfactory method comprises melting the sodium under'thesurface of a suitable liquid, such as :qrlene, followed by violentagitation. such as with a turbo-mixer, and cooling with agitation. Othermethods which may be used include extrusion through fine orifices, andthe generation of an arc between sodium electrodes in an inert liquid.

Although almost any desired concentration of treating agent in thesuspending medium may 75- The type and concentration of the unsaturatedhydrocarbon or unsaturated hydrocarbon fraction to be treated also has aconsiderable influence upon the method of operating the process. Thus,with a highly concentrated butadiene, such as 98% butadiene, therefining reagent should preferably contain a fairly low concentration of.active agent, and a fairly high concentration of inhibitor, to minimizelosses due to polymerization.

I generally prefer to employ a fraction of such concentration, and withsuch proportion of suspending medium, that the actual concentration ofunsaturated hydrocarbon, such as butadiene, in the reaction zone is lessthan and, more preferably, less than 70%. Excellent results are obtainedwhen the actual concentration of unsaturated hydrocarbon in th reactionzone is less than 60%.

The process may be carried out at any desired pressure, such asatmospheric, subatmospheric. and superatmospheric pressures.

The temperature at which the process is conducted also has a veryconsiderable bearing upon the degree to which the fraction is refinedand the losses incurred due to polymerization. Although the optimumreaction temperature to be employed is dependent largely upon otherfactors, such as the concentration of both the unsaturated hydrocarbonand the refining reagent in the reaction zone, I generally prefer toconduct the refining operations at temperatures below 100 C. and, moreparticularly, below 80 C. Excellent results are obtained by conductingthe refining operations at temperatures below 70 C.

The rate at which the material to be refined is passed through therefining reagent has a very considerable effect upon the degree to whichthe impurities present are removed, although this is dependent to someextent upon other variables such as the concentration of refining agentin the suspending medium and the temperature at which the refiningoperations are being conducted. While it is difiicult'to establish exactlimits for optimum throughputs under'all conditions, I generally prefernot to exceed a throughput of material to be treated on an hourly basisof more than four times the weight of suspending medium employed andmore preferably, not more than twice the weight of the suspendingmedium. Excellent results are obtained when not more than equalquantities of material to be treated, upon an hourly basis, are passedthrough the suspending medium.

It will be recognized that the contact time between the material to betreated and the reagent is determined both by the thickness of the layerof refining reagent employed and by the rate at which the material to betreated is passed through the reagent.

The method employed for introducing the maauaaso terial to be refinedinto the'refining reagent also has some influence upon the extent towhich,

be said that a fine stream or jet of the liquid or gaseous material tobe refined is desired. This may be accomplished by introducing thematerial to be treated into the refining reagent by means of suitableorifices, jets, nozzles, or other subdividing means. Porous objects ormaterials also may be employed fm this purpose, such as porous ceramicor glass diflusing blocks or units.

As the refining agent may show some tendency to settle out in the bottomof the treating vessel or unit, the jets or nozzles by means of whichthe material to be treated is introduced into the unit may be soarranged as to prevent any undue settling of this material. In verticalvessels, this may be accomplished by locating these units in such a wayas to impinge the inlet stream or streams upon the bottom of thetreating vessel.

The inlet jets also may be arranged tangentially to impart a swirling orcircular motion to the refining reagent, if desired. Another methodcomprises locating the inlet jet or jets directly in the bottom of thereactor, or tangentially in the sides of the reactor, or both, toprevent any settling in the bottom of the reacting vessel and/or toimpart any desired circular or other motion to the'refining reagent.

Any desired combination of these methods also may be employed, such asthe use of a jet or jets directly impinging upon the bottom of thereactor in conjunction with the use of a tangential jet or jets toprevent the active agent from settling out and depositing on the wallsof the reactor and/or to maintain the refining reagent in any desiredstate of agitation.

The refining reagent also may be' maintained in the desired degree ofagitation by the use of suitable stirring or mixing devices, or by theuse of circulating pumps, or by a combination of these methods, orotherwise. One or more of these methods also may be used in conjunctionwith one or more of the methods discussed previously to maintain thesystem in the desired degree of dispersion.

It should be pointed out, however, that the use of such agitationmethods is not required in most cases. Thus, excellent results have beensecured by conducting the refining operations in a tower,

the material to be treated being introduced into the bottom of the towerby means of a small orifice. The passage of the fraction being treatedin the gaseous state upward through the column was found to maintain thesystem in-the desired degree of agitation. f

The refining agent, particularly when finely divided sodium is employedfor-this purpose. usually acts both as a reactant and as'a polymerizingagent for the removal of undesired impurities. Thus, in the case oflight oil butadiene fractions containing monovinylacetylene, otheracetylenes, aldehydes, and other oxygenated impurities, the sodium willreact with at least a portion of the monovinylacetylene present to formsodium monovinylacetylide, and may react'with certain of the oxygenatedderivatives to form corresponding derivatives. At least a portion of theacetylenic hydrocarbons present also are polymerized to form polymers,or copolymers with other unsaturated hydrocarbons present, whichfrequently are insoluble in nature- Certain of the oxygenatedderivatives, such as aldehydes, also may be.

may be reacted with carbon dioxide to form-umsaturated acids,-orotherwise.

- 10 polymerized to form polymers which may be insoluble in type.

As a result, the refining of butadiene fractions with a suspension offinely divided sodiumin the presence of an inhibitor is characterized bythe radual accumulation oi insoluble polymers de-' rived from theimpurities present in the unsatu-,

rated hydrocarbon. These may be removed in any desired manner, such asby filtration, which may be carried out continuously during the refiningoperation, or may be carried out in a batchwise manner after thetermination of the refining step.

As the removal of the insoluble polymers also is attended by some lossof refiningagent, even when the latter is in a very fine state 01'subdivision, it is advisable in many cases to continue the refiningoperations until the refining agent has been largely or completelyexhausted before filtering. y

The solid or semi-solid filtered products may be treated to recover anydesired materials or they maybe disposed of in any suitable manner.Thus, any unchanged refining agent, such as sodium, may be recovered bymelting and coalescing operations, or by amalgamation with mercury, or.

tallic acetylides, may be decomposed with water to regenerate thecorresponding acid or they Any inhibitor present also may be recovered-A convenient method for the disposal of the insoluble polymers comprisestreatment with carbon dioxide, suitably in the presence of traces ofmoisture, followed by filtration.

As the cost of the treating process is largely a function of thequantity of the reactive agent employed in the refining operations, theefiicient utilization of such agent is of considerable im-' portance. Adesirable method for insuring optimum utilization of the treating agentis to carry out the operations. in a continuous countercurrent manner.the reagent moving throughthe system in a manner countercurrent tothatof the material to be treated.

This may be illustrated by means of a consideration of a simplecontinuous countercurrent system comprising two treating towers orvessels. The material to be treated is passed into the first tower,which contains a partially exhausted re-, agent. This serves to'remove asubstantial por. tion of the impurities present, after which thepartially refined material passes into the second tower, which containsa i'resh, or more highly concentrated, reagent. This serves to removethe impurities present to the desired extent. The

process is continued until the reagent in the first tower is almost, orcompletely, exhausted, after which it is discarded and the partiallyexhausted reagent from the second column substituted for it. Freshreagent then is added to the second column.

In this manner the material to be treated and the refining reagent passthrough the system countercurrent to each other, the first continuouslyand the second in a discontinuous manner.

This may be modified such as by the continuous addition or fresh reagentto the second tower, the continuous transfer of partially exhaustedreagent to the first tower, and the continuous withdrawal of morecompletely exhausted, or exhausted, reagent from the first tower. Acom-' pletely continuous countercurrent treating system thus isachieved.

Any desired modification of these methods may be employed, and anynumber of treating towers or units may be used. It will be observed thatin each of the cases discussed, the incoming material to be refined iscontacted with partially exhausted reagent (maximum concentration ofimpurities-minimum concentration of active agent) while the outgoingmaterial to be refined is contacted with fresh or more highlyconcentrated reagent (minimum concentration of impurities-maximumconcentration of active agent), Thus the two objectives to be sought.namely, practically complete, or complete, utilization of the activeagent and substantial, or practically complete, removal of impuritiesfrom the material to be refined, are achieved.

As the limiting factor affecting the utilization of the active agent isthe proportion of insoluble polymers and/ or residues which can becontained therein without seriously impairing its flowing properties, orthe passage ofthe gaseous material to be treated therethroush, itfrequently happens that the quantity of insoluble material present isinsufiicient to interfere seriously with the operation of the processwhen the refining agent present has been almost completely exhausted. Inthis case, the operation of the unit may be continued by the additionthereto of an additional quantity of the refining agent, and thisprocess may be continued until the concentration of insoluble materialin the refining reagent renders it too viscous to be used further in theprocess in a satisfactory manner.

In this connection, it is well to point out that the insoluble productsformed during the reaction Example 2 amine. The operations were carriedout in a 2" column at a temperature of 50 C. and atmospheric pressure.The finely divided sodium was prepared by agitation of molten sodiumunder the surface of xylene by means of a turbo-mixer. followed bycooling with continuous agitation. Under the operating conditionsemployed, the actual refining medium comprised a 10% sodium suspensionin a suspending medium containing approximately 90% xylene and 10%butadiene fraction. The height of refining reagent employed was 5 feet.

The refining operation was continued for a period of 30 hours, thebutadiene fraction being charged at the rate of approximately 900 gramsper hour.

The refined butadiene fraction obtained contained only 0.002% acetylenesand less than 0.001% aldehydes. Only negligible quantities of thebutadiene was lost in the form of soluble polymers, and otherwise.

Example 3 A 50% light oil butadiene fraction containing 1.0% acetylenesand 0.04% aldehydes, was passed are converted on prolonged contact withthe refining reagent to viscous and/or insoluble products, their removalfrom the suspending medium,

suitable at the end of a/refining cycle and prior to the return of thesuspending agent to the system, may be indicated. 0n the other hand,certain of these soluble polymers are sufllciently stable to act as asuspending medium for the refining agent.

The process may be more completely illustrated by means of the followingexamples.

Example 1 A 3800 gram portion of a 40% light oil butadiene fractioncon-taining 1.02% acetylenes and 0.05% aldehydes was treated in anautoclave at a temperature of 50 C. with a suspension of 23 continuouslyinto the bottom of a 2" steel column containing a xylene suspension ofvery finely divided sodium at a temperature of 50 C. and a pressure of50 pounds per square inch, gauge. The treating medium contained 0.05% ofa substituted polyphenol as a polymerization inhibitor.

Under the operating conditions employed, the actual suspending mediumwas a mixture of 24% of xylene and 76% of the butadiene fraction. Thequantity of finely divided sodium employed was grams, representing a 7%suspension in the indicated suspending medium.

The run was continued for a total of 31 hours at an average chargingrate of 840 grams per 'hour, the total quantity of butadiene fractioncharged being approximately 24,000 grams.

The refined butadiene fraction contained only 0.02%acetylenes and 0.001%aldehydes. The quantity of soluble polymers produced was 29 grams, orapproximately 0.1% by weight of the total fraction refined.

In the specification and in the claims, the following terms have theindicated meanings.

The term polymerization inhibitor" is intended to include one or morecompounds or materials which serve to retard, or entirely prevent, thepolymerization of unsaturated hydrocarbons in the presence of an activerefining agent.

The term a metal of group Ia and group m: of the periodic system isintended to include lithium, sodium, potassium, rubidium, caesium,barium, strontium, and calcium, as well as active alloys or compoundscontaining one or more of such metals as an essential ingredient.

The term finely divided is intended to mean a material reduced to such astate of fineness that the preponderating part is composed of particleshaving a diameter of less than 0.05", as well as materials in thecolloidal or dissolved form.v

While reagents and procedures of a particular nature have beenspecifically described, it is to be understood that these are given byway of made within the scope of the claims without de- Parting from thespirit of the invention, which is intended to be limited only asrequired by the prior art.

I claim:

1. A process for refining a light oil diolefin fraction containingdiolefine material and contaminated with impurity including acetylenicmaterial comprising passing said fraction through it dispersion of atleast one finely divided metal selected from the group consisting ofmetals of group IA and group HA of the periodic s stem in the presenceof a polymerization inhibi or at a temperature below 100 C. whilemaintaining the concentration of diolefine material in the reaction zoneat less than 80% and a rate of flow per hour of said fraction throughsaid dispersion of not more than four times the weight of dispersionmedium employed, said dispersion being at least one foot thick in thedirection of flow of said fraction, and removing said diolefine materialfrom contact with said dispersion prior to the polymerization of thelarger part thereof, said removed diolefine material being lesscontaminated with impurity including acetylenic material.

2. A process for refining butadiene contaminated with impurity includingmonovinyl acetylene comprising passing said contaminated butadiene at atemperature below 100 (land in the presence of less than by weight of apolymerization inhibitor through a dispersion of at least one finelydivided metal selected from the group consisting of metals of group IAand group IIA of the periodic system at a rate of flow per hour of lessthan four times the weight of dispersion medium employed whilemaintaining the concentration of butadiene in the reaction zone at lessthan 80%, thedepth of said dispersion being at least one feet thick inthe direction of flow of said butadiene, and removing said butadienefrom contact with said dispersion prior to the polymerization of a largeproportion thereof, said removed butadiene being less contaminated withmonovinyl acetylene.

3. A process for,refining butadiene contaminated with impurity includingacetylenic material which comprises passing said contaminated butadienethrough a dispersion containing up to 30% by weight thereof of a finelydivided alkali .14 polymerization of a large proportion thereof, saidremoved butadiene being less contaminated with impurity includingacetylenic material.

4. A process for refining a light oil butadiene fraction contaminatedwith acetylenic material which comprises passing said fraction upwardlythrough a dispersion containing'up to 20% by weight thereof of a finelydivided alkali metal in the presence of less than 5% by weight of apolymerization inhibitor at a temperature below 80 C. while maintainingthe concentration of butadiene in the reaction zone at less than 70%,said dispersion being at least two feet in thickness in the direction offlow of said butadiene and being maintained in agitation by the passageof the contaminated butadiene therethrough at a rate' of flow per hourequivalent to les than twice the weight of dispersion medium employed,and removing said butadiene from contact with said dispersion prior tothe polymerization of a substantial proportion thereof, said removedbumetal in the presence of up to 5% by weight of a polymerizationinhibitor at a temperature below 80 C. while maintaining theconcentration of butadiene in the reaction zone at less than saiddispersion being at least two feet thick and the rate of flow of saidcontaminated butadiene through said dispersion being not more than twicethe weight per hour of the dispersion medium employed, and removing saidbutadiene from contact with said dispersion prior to the tadiene beingin a form less contaminated with acetylenic material.

5. A process for refining butadiene contaminated with impurity includingacetylenic material comprising passing said contaminated butadieneupwardly in vapor phase through a dispersion containing less than 30% byweight of finely divided alkali metal and containing less than 10% byweight of a polymerization inhibitor at a temperature below 100 C. whilemaintaining the concentration of butadiene in the reaction zone at lessthan by weight, the depth of said dispersion being at least one foot inthickness in the direction of fiow of said butadiene and the rate offlow per hour of said butadiene being not, more than four times theweight of dispersion medium employed, and removing gaseous butadienefrom'contact with said dispersion prior to the polymerization of a largeproportion thereof, said removed butadiene being less contaminated withimpurity including acetylenic material.

6. A process for refining butadiene contaminated with impurity includingacetylenic material comprising passing said contaminated butadienethrough a dispersion containing less than 30% of finely divided sodiumthe majority of the particles of which have a diameter of not more than0.05" ata temperature below C. while maintaining the concentration ofbutadiene in the reaction zone below 80%, said dispersion being at leastone foot thick in the direction of flow of said butadiene and containingless than 10% by weight of a polymerization inhibitor, the rate offiowper hour of said butadiene being not more-than four times the weightof dispersion medium employed, and removing said butadiene from contactwith said dispersion prior to the polymerization of a large proportionthereof, said removed butadiene being less contaminated with saidimpurity including acetylenic material.

FRANK J. SODAY.

